Firstly, don't panic. Your Yoti is protected by multi-factor authentication. It’s linked to your phone, protected by a PIN that only you should know and uses facial recognition for added security. Hopefully, you've also got a lock screen on your phone with a strong code or fingerprint.
If you stored a recovery key in iCloud or Google Drive after you created your Yoti, you can install the Yoti app on a new phone, and will be able to recover your account when you log back in with your PIN.
If you haven't created a recovery file, you will need to create a new Yoti as if you never had one before.